Muscle & nerve
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Clinical Trial
Intrathecal baclofen for spasticity-related pain in amyotrophic lateral sclerosis: efficacy and factors associated with pain relief.
Clinical signs and symptoms of spasticity include hypertonia, involuntary movements (spasms, clonus), decreased range of motion, contractures, and often spasm-related pain. When spasticity is refractory to medical management, patients may be referred for intrathecal baclofen (ITB) pump placement. We reviewed a cohort of amyotrophic lateral sclerosis (ALS) patients with intractable spasticity requiring ITB to further define the impact of ITB on pain relief in this patient population. ⋯ Six patients (75%) experienced pain score reduction, three of whom had complete pain relief. Postoperative pain reduction was predicted by the degree of pain reduction following preoperative ITB test injection. These results support ITB as a treatment modality for pain associated with spasticity in ALS.
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To test the hypothesis that the anterior horn cells become hypoexcitable in the absence of central drive, we recorded F waves simultaneously from the first dorsal interosseous (FDI) and the abductor digiti minimi (ADM) before and after volitionally inactivating one muscle (target) while periodically contracting the other muscle (control). In 14 healthy subjects, F waves recorded from the target muscle showed a progressive decrease in persistence and amplitude (whether counting all 100 trials or only detectable responses) after muscle relaxation for 1, 3, and 6 hours, followed by a quick recovery upon brief muscle contraction. We conclude that volitional inactivation suppresses the F waves of the target muscle without equally affecting the control muscle innervated by the same nerve. The history of activity of a muscle should therefore be taken into account in clinical testing, especially when the study of a paretic muscle shows abnormal F-wave excitability.